From a low point
perhaps fifty
years ago, otters have been slowly staging a comeback in Contra Costa
County. They have gradually recolonized many of our creeks,
learning to cope with flood control structures and other unnatural
objects as they get around. They can walk cross country to move
from one creek to another. Once they find a good spot, they
stay until prey (fish and crayfish) becomes hard to find. Then
they move on.

They have visited Heather Farm Park in
Walnut Creek for many years, but recently they have been staying
longer, there are more of them, and there has been breeding
activity. Otters range as far south as San Ramon now and can be
seen in Walnut Creek at Civic Park and in Las Trampas Creek. Much
of this renaissance is due to cleaner water. For otters to
flourish, they need two things from humans: high quality water
and protected wildlife corridors so they can move around.

Beavers Are Also Returning

The famous Martinez beavers aren't the only ones in the area. As
early as 2009, we saw beaver tooth marks on a tree in Civic Park in
Walnut Creek. A year or two later we saw debris in the water that
could possibly have been the beginning of a dam.

In
2013 this became unmistakable. A number of cottonwoods were
girdled. Upstream, trees were felled and a dam begun. It
washed out after rather a small storm and the beavers abandoned
it. Perhaps the current was too strong, or they concluded there
wasn't enough to eat. We never saw this beaver or beavers, but
they were likely to be young and inexperienced, expanding into new
territory after leaving their parents. We have not seen any signs
of beavers since.

Beavers are problematical in densely populated areas because they
destroy vegetation in order to eat, and they alter stream flow when
they build their dams, sometimes even causing floods. On the
other hand, beavers are very good at creating habitat. Their dams
would be a benefit in the hills, where the ponds they create would
provide water for wildlife in the summer, and with it, a greater
variety of plant species and new habitat niches to meet wildlife's
needs.

Otter eating a freshly-caught trout in the front pond at Heather Farm
Park in Walnut Creek. Two recently installed floating islands
have created habitat and improved water quality.Photo by Rick Kelsch

Beaver dam under construction in Civic Park, November 2013Photo by Jim Hale